This Week in Biotech

With the SPDR S&P Biotech Index up 37% over the trailing-12-month period, it's evident that investment dollars are willingly flowing into the biotech sector. Keeping that in mind, let's have a look at some of the rulings, studies, and companies that made waves in the sector last week.

Cleared for launch As always, let's dive right into some of this week's most uplifting stories and studies. Dendreon (NASDAQOTH: DNDNQ) shareholders received a rare glimpse of good news this week, after the European Commission announced the marketing authorization of its advanced prostate cancer immunotherapy vaccine Provenge. The approval shouldn't be a huge shock as the Committee for Medical Products for Human Use (the EU equivalent of the FDA's advisory panel) recommended marketing authorization for Provenge in June. The big question now for Dendreon is whether the product will sell overseas. It's trimmed its costs (and jobs) domestically, but it's seen sales of its vaccine slump because of tough competition. This is definitely good news for Dendreon; but make no mistake, plenty of uncertainties remain.

Clinically impressive On the clinical data front, we had three studies that produced cheer-worthy results: two early stage results and one late-stage.

Small-cap Omeros (NASDAQ: OMER) took the crown as the week's top performer on a percentage basis, gaining 41%, after announcing positive phase 1 data on OMS824 for the treatment of stable schizophrenia, initiating a phase 2 study on OMS824, and receiving a mammoth price target hike from Wedbush Securities to $28 from $18 (implying a 291% upside from Friday's close). While Wedbush is more focused on Omeros' eye drug OMS302 which it's filed a new drug application for, the near-term excitement was over OMS824 which inhibits PDE10, an enzyme found in the brain that affects cognition. The idea here is that Omeros' PDE10 inhibitor could have positive effects on patients with schizophrenia and Huntington's disease. We should know more in a couple of months when Omeros reports its top-line mid-stage results.

Antisense drug developer Isis Pharmaceuticals (NASDAQ: ISIS) joined the early stage party on Thursday by releasing add-on data for ISIS-SMNrx, an early stage compound to treat spinal muscular atrophy in children. According to Isis' study, the two highest doses of ISIS-SMNrx (6 mg and 9 mg) demonstrated improvement in muscle function tests after 14 months even though just a single injection of the drug had been given. In the highest dose cohort none of the children demonstrated a performance decline which was particularly encouraging. Isis is expected to report additional data on ISIS-SMNrx later this year or early next year, with late-stage studies on the drug expected to begin in early 2014 if all the data continues to go well.

Turning to late-stage data, Repros Therapeutics (NASDAQ: RPRX) reported additional encouraging top-line results on its oral drug Androxal for secondary hypogonadism on Wednesday. Like its previous late-stage trial, Androxal met its co-primary endpoints which revolved more around safety than anything else. Specifcally, Androxal was noted as achieving "highly statistically significant and relevant improvement in testicular function" which would lend it a good chance for an eventual approval as it separates itself as the potential superior treatment among those with secondary hypogonadism. This is certainly a developing drug worth keeping your eyes on.

Battleship sunk?And then there was Prosensa (NASDAQ: RNA) , which was annihilated this week, losing 70% alone on Friday, after announcing that its co-developed drug with GlaxoSmithKline for Duchenne muscular dystrophy, drisapersen, failed to meet its primary and secondary endpoints in a 186-patient late-stage study. According to the press release, drisapersen failed to produce statistically significant improvements relative to the placebo and didn't demonstrate any changes in motor function during the trial. With Prosensa's additional ongoing studies both utilizing exon-skipping technology, and it having failed here in a large late-stage study, investors are visibly worried -- and with good reason. The two companies do plan to study the clinical data for possible future studies, but for all intents and purposes investors have completely written off drisapersen as a lost cause.

Nothing tops this investing strategyIt's no secret that the many biotech stocks have been soaring recently, but news of Prosensa's late-stage failure serves as the perfect reminder that the best investment strategy is to pick great companies and stick with them for the long term. The Motley Fool's free report "3 Stocks That Will Help You Retire Rich" not only shares stocks that could help you build long-term wealth, but also winning strategies that every investor should know. Click here to grab your free copy today.

Fool contributor Sean Williams has no material interest in any companies mentioned in this article. You can follow him on CAPS under the screen name TMFUltraLong, track every pick he makes under the screen name TrackUltraLong, and check him out on Twitter, where he goes by the handle @TMFUltraLong.

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